1. Field of the Invention
The present invention relates to bearings for use in automotive engines, and particularly to main bearings supporting the crankshaft of a reciprocating internal combustion engine.
2. Related Art
Many machines, particularly internal combustion engines, utilize plain bearings for mounting rotating shafts such as a crankshaft of a reciprocating engine. Crankshafts present a special need because lubrication is required not only for the crankshaft's main bearings, but also for the bearing journals upon which connecting rods ride. In order to permit lubrication of connecting rod journals, most engines use the prior art oil transfer scheme illustrated in FIG. 3. As shown in FIG. 3, crankshaft 102 is mounted between a lower insert, 110, and an upper insert, 106. An oil groove, 114, is included to supply oil to a drilling in the crankshaft. The drilling allows oil to be picked up and sent to the crankshaft's connecting rod journals. The length of the oil groove must be sufficient to furnish a required quantity of ail to one or more connecting rod journals. With the arrangement shown in FIG. 3, oil groove 114 terminates at both ends within the parting line regions between lower insert 110 and upper insert 106. Because these regions have the greatest bearing clearance, more oil is allowed to leak through this region, and the oil pressure within not only groove 114, but also the remaining portions of the engine, is reduced. As a result, less oil is caused to enter the drilling of crankshaft 102. It would be desirable to provide a main bearing construction in which less of the oil is allowed to leak past the crankshaft main bearing journal, while maintaining, or even increasing, the length of the bearing's oil groove, thereby boosting the oil pressure within groove 114 while making more oil available to the connecting rod bearings, or enabling the usage of a smaller oil pump.